The proposed work is centered about two aspects of ocular physiology, a) cornea and b) aqueous humor dynamics. a) Cornea: Studies will be made to examine the effects of various compounds and procedures on the structural and functional integrity of the endothelium. Compounds such as preservatives used in ophthalmic solutions, and clinically used procedures such as photocoagulation will be tested both in vivo and in vitro. Solutions will be sought which are most suited to enhancing corneal viability over intermediate time periods, in order to allow better preservation of the endothelial bicarbonate transport system. b) Aqueous humor dynamics: The membrane characteristics (solute permeability and reflection coefficient) of the in vivo ciliary epithelium will be determined by measurement of plasma: aqueous ratios at different time intervals and the data analyzed by a series of equations designed to allow the determinations of the characteristics in the untouched eye. Further studies will be made to identify potentially useful tetrahydrocannabinol derivatives which are effective in reducing intraocular pressure. Measurements will be made of the forces underlying the process of aqueous humor formation, including direct measurements of capillary pressure in the ciliary processes.